U.S. Pat. No. 3,313,409 discloses an apparatus for inspecting glass containers in which a starwheel conveys containers in sequence through a series of inspection stations. At one of the inspection stations, selected dimensional parameters of each container are inspected by contacting the container with rollers coupled to sensors, and rotating the container about its central axis so that the sensors provide output signals that vary as a function of variations of the container parameters. Specifically, container height, sealing surface warp and dip, and cocked orientation of the container finish are measured by rollers that engage the container sealing surface as the container rotates. The rollers are coupled to LVDT sensors that provide analog electrical signals indicative of deviations or variations in height (level) at the sealing surface. These signals are fed to appropriate electronics to energize a reject plunger for separating a container from the conveyor line if the measurement signals depart from desired standards and specifications. The rollers in contact with the container sealing surface are subject to mechanical wear, and can cause contamination at the sealing surface. Furthermore, the size of the rollers limits the size of containers in connection with which they may be employed, and the size (resolution) of height variations that can be detected. The moving parts require maintenance and repair. Furthermore, the roller construction is not adapted to measure height of any wire-edge or over-press within the sealing surface lip.
U.S. Pat. No. 4,945,228 discloses an apparatus for inspecting the sealing surface area of a container finish that includes a light source positioned to direct light energy onto the container sealing surface as the container is held in stationary position and rotated about its central axis. A camera, which includes a linear array or matrix (area) array of light sensitive elements, is positioned and oriented with respect to the container axis of rotation to receive light energy reflected by the sealing surface, with the camera having an effective field of view limited to an angular portion less than the entire circumference of the container sealing surface. The camera array is scanned at increments of container rotation to develop information indicative of intensity of light at each array element as a function of such increments, and commercial variations at the container sealing surface are detected as a function of such information. The apparatus so disclosed is well adapted to detect commercial variations that affect reflectivity of the container sealing surface, such as line-over-finish variations, blisters, stones and a dirty container finish. However, the apparatus so disclosed is not adapted to measure dimensional parameters of the container finish, such as height of the container sealing surface, warp, dip or cock at the container sealing surface, and/or height of any wire-edge or over-press at the sealing surface (The term "commercial variations" refers to variations that can affect commercial acceptability of the container. The term "sealing surface area" refers not only to the sealing surface itself, but also to any wire-edge, over-press or other commercial variation at the sealing surface.)
U.S. Pat. No. 5,489,987 discloses an apparatus for inspecting the sealing surface area of containers that includes a light source positioned to direct a narrow beam of light energy at an acute angle onto the sealing surface area of a container as the container is rotated about its central axis. A light sensor is disposed to receive the narrow beam of light energy reflected from the sealing surface area, and provides an output signal that varies as a function of position of incidence of the reflected light beam on the sensor. That is, the reflected light beam is incident on the sensor at a position that varies with height or level of the sealing surface with respect to the light source and sensor, and the sensor is characterized by providing an electrical output signal that varies as a function of position of incidence of the reflected light beam on the sensor. Variations in height at the sealing surface area are detected as a function of the sensor output signal. In one embodiment, light source/sensor pairs are disposed on diametrically opposed sides of the container axis, and warp, dip and/or cock at the sealing surface of the container is detected as a combined function of variations in position of incidence of the reflected light beams on the sensors as the container rotates.
U.S. Pat. No. 5,896,195 discloses an apparatus for inspecting the sealing surface area of a container finish that includes a structured light source positioned to direct a collimated-line shaped light beam onto the sealing surface area of a container as the container is moved, either laterally or rotationally, relative to the light source. The line-shaped beam at the container sealing surface area has a long dimension orthogonal to the container axis that extends chordally across the sealing surface area, and a narrow dimension tangential to the container axis. A light sensor is disposed to receive portions of the line-shaped light beam reflected from the sealing surface area, and provides an electrical output signal that varies with height or level of the sealing surface with respect to the light source and sensor. The sensor is coupled to associated electronics for providing information indicative of sealing surface height. The elongated dimension of the line-shaped beam at the container sealing surface area accommodates wobble or misalignment of the sealing surface area with respect to the light source and sensor. Furthermore, the elongated radial dimension of the line-shaped light beam at the container sealing surface are a produces a reflection on the sensor from any wire-edge or over-press within the container mouth, thus producing at the sensor information indicative of both existence and height of any such wire-edge or over-press.
Although the apparatus disclosed in the noted patents overcome problems theretofore extant in the art, further improvements remain desirable. For example, the apparatus disclosed in U.S. Pat. No. 5,489,987 employs narrow field detectors mounted on one or both sides of the sealing surface, for which placement is critical and which can fail to receive a signal from the container if the container moves out of alignment. The apparatus disclosed in U.S. Pat. No. 5,896,195 overcomes this problem, but presents an additional problem in which it is at least possible to receive stray reflections, such as from chordally opposite areas of the sealing surface, that can confuse or obscure height measurement on one side of the sealing surface. It is therefore a general object of the present invention to provide an improved apparatus and method for inspecting the sealing surface area of containers for unacceptable commercial variations. Another and more specific object of the present invention is to provide an apparatus and method of the described character that are adapted to inspect the sealing surface area of a container for multiple types of variations in a single operation and at a single inspection station. A further object of the present invention is to provide a method and apparatus of the described character for inspecting both optical and dimensional characteristics of the sealing surface area of a container finish.
It is another object of the present invention to provide an apparatus and method for measuring or determining dimensional characteristics of a container finish, particularly a container sealing surface area, of the type disclosed in the above-noted U.S. Pat. No. 5,489,987, in which the measurement process is characterized by improved immunity to positional variations or wobble at the container sealing surface, and to stray reflections within the measurement area. Another object of the present invention is to provide a method and apparatus of the described character that attain the foregoing objective while being economical to implement and reliable over an extended operating lifetime. A further object of the present invention is to provide a method and apparatus of the described character that, in alternative embodiments, may be implemented at either the hot end or the cold end of a glassware manufacturing system.